IMHO, Fort Knox (and Liberty) safes are just about the best out there. However, they are priced accordingly.
You have to look at the features you get for that extra money they cost. This can sometime includes obvious things like the number of bolts. It also sometimes includes not so obvious features like – say - better relockers or drill plates with embedded ball bearings.
Do you feel these features are likely to benefit you?
Also, the extra money can involve simply convenience features.
For example, my Fort Knox has a screw that allows me to adjust the door closure so that there is no wiggle at all when the door is locked. Some cheaper safes simply have a welded steel tab that must be adjusted trial-and-error with a hammer to accomplish this.
As a practical matter, I’m not sure most folks (including myself) really need the nice features that come with a Fort Knox. In most burglaries, just about any decent safe will work.
However, I’d stay away from super cheap safes. They are going to look good on the outside, but probably will be missing basic, but hidden, security features like drill deflection plates or such.
I wouldn’t even consider a safe that doesn’t have a UL Residential Security Container rating.
Two other things:
First, get the thickest steel that you can. I believe its pretty well known nowadays that thinner safes can be easily gotten into with certain common electric tools.
Second, make sure the thing is much too heavy to move and/or is securely anchored. If the bad guys can get the safe into a vehicle, they can later open it at their leisure.
Just my own opinions, of course.